Circuit breaker



Dec. 22, 1953 J. A. DROBNEY ETAL,

CIRCUIT BREAKER 2 Sheets-Sheet 1 Filed Feb. 7, 1952 Tripped $5 Gas yn mm E m? N m WAm w INN A Rd wmmw WITNESSES: $471,! a 7 z Dec. 22, 1953 J. A. DROBNEY ET AL 2,663,773

' CIRCUIT BREAKER Filed Feb. '7, 1952 2 Sheets-Sheet 2 I 34 --27 -45 GD 33-$ 'fl-rg 32 Fig.3

53 a m ,l9 33 29 Fig.5

WITNESSES:

INVENTORS Joseph A. Drobney and Paul W. Brown.

Bi] ATTON Patented Dec. 22, 1953 Joseph Drolmey,

Duquesne, and Paul Brown, Beaver Falls, Pa., assignorstoIW-esitinghouse Electric Corporation, East Pittsburgh,

Pa, a corporation of Pennsylvania Application February 7, 1952, SerialNo. 270,401

11 Claims. 1

"This invention relates to circuit breakers and more particularly to circuit .breaker for controlling lighting and moderate power circuits.

An object of the invention is to provide-a circuitbreaker embodying a bimetallic switch member operative to enact automatic opening of the breaker and having spring means biasing the switch member closed in the closed position of the breaker and which also biases the switch member open in the open position of thebreaker.

Another object of the invention isto provide a circuit breaker that is trip free of the manual operating means wherein a thermally responsive element constitutes both the movable contact carrying means and the trip means and cooperates with an cvercenter spring to form the automatic opening means.

Another object of the invention is to provide a circuit breaker having a minimum number of parts, of rugged construction and reliable in operation and inexpensive to manufacture.

The novel features that are considered characteristic of the invention are set forth in the appended claims. The invention itself, however, both as to structure and operation, together with additional objects and advantages thereof will be best understood from the following detailed description when read in conjunction with the accompanying drawing.

In said drawing:

Figure 1 is a side elevational view partly in section with the cover plate substantially broken away of a circuit breaker embodying the principles of the invention, the breaker being shown in the closed position.

Fig. 2 is a side elevational view similar to Fig. 1 but showing the breaker in the automatically opened position.

Fig. 3 is a horizontal sectional view taken along line III-III of Fig. 1.

Fig. 4 is a vertical sectional view taken along line IVIV of Fig. 1.

Fig. 5 is a horizontal sectional view taken substantially along line VV of Fig. 1

Fig. 6 is a perspective view showing a part of I the operating mechanism.

Referring to Fig. 1 of the drawing, the circuit breaker comprises an enclosing housing I l and a cover plate I3 (a fragment only of which is shown) both made of insulating material, a stationary contact l5, a movable contact IT and an operating handle IS. The stationary contact I5 is mounted on the inner end of a conducting strip 2| which is laid into an opening in the housing I l and has a terminal connecting means 23 at the outer end thereof. 'I he movable contact I is carried on the end of a thermally responsive movable switch member -25 which is composed or a strip of bimetallic material. The -=bimetallic switch member :25 :is welded or otherwise suitably secured to a pivot pin i mounted for-rotation in companion openings in the side wall of thehousing H andthe-cover H.

The bimetallic switch member liadjacent the end thereof opposite to the contact 1 1 is provided with a shouldered portion 4-9 on which is mounted an angularoperati-ng member -34 pressed against the shoulders by means of an overcenter spring 33. In the closed pdsitionof the breaker, the overcenter spring 33 together with the portion of the bimetallic switch member 25 to the left of the pivot pin :2! torms a toggle having its knee .joint at '29 by which the spring 33 biases the contact l-5"l-'l closed and provides contact pressure. p

A flexible conductor -34 connects the bimetallic switch member '26 at a point adjacent the left hand end thereof to the inner end of a conducting strip 35 which at its outer end carries a terminal connector 38. p

The operating-handle I9 is :pivotally mounted on pivot projections 3-5; supported in the side wall of the housing H and the cover 13. The handle l9 extends outwardly through an opening -31 in the housing, whichopeningis substantially closed in all positions of the handle by a. circular portion 39 of the handle IS. A spring H having one end hooked over a pin 43 extending between two bifurcated portions of the handle 19 and the other end attached to the bimetallic switch member 25 at a point to the left of the pivot pin 21 biases the handle is to the on position and biases the bimetallic switch member 25 in aclockwise or opening direction about the pivot 21.

With the handle it in the on position, however, the spring 4| has i-nsuflicient force to overcome the spring 33 and move the switch member to the open position-. When the handle 19 is moved as far as it will go in a clockwise direction to the off position, the tension of the spring 4| is increased to the point where it overcomes the force of the overcenter spring '33 and moves the toggle 33-25 overcenter and moves the bimetallic switch member 25 to the open position with a sna action. A shoulder 44 on the housing ll acts as a stop to limit the opening movement of the switch member.

When the handle I9 is moved to the on position spaced projections 45 on the inner "end thereof are moved to a position above the ends 32 of the actuating member 3| as shown in dot and dash lines at 55a in Fig. 2. When the handle !9 is moved counterclockwise to the on position the projections 45 engage the spaced ends 32 of actuating member 3! and moves the toggle 3325 overcenter in closing direction. As soon as the toggle is moved overcenter the spring 33 acts to move the switch member 25 to the closed position to close the contacts with a snap action.

The circuit breaker is opened automatically in response to low overload currents of, for instance, up to ten times normal rated current by the bimetallic switch member 25. The high expansion side of the bimetal 25 is on the lower side, consequently, as the bimetal becomes heated by the flow 01' overload current the ends of the bimetal tend to move upwardly. Since the contact end of the bimetal switch member cannot move upwardly and since the bimetal is mounted on the pivot 21 the distortion of the bimetal will cause a slight clockwise rotation of the bimetal element about the pivot 27 and at the same time cause upward movement of the left end thereof. This action will compress the spring 33 and cause upward overcenter movement of the toggle 33-45, whereupon the spring 33 will move the switch member 25 to the open position to open the contacts with a snap action.

When the bimetallic switch member 25 moves to the open position during an automatic opening operation, the tension of the spring 4! is reduced to a point where a spring 41, compressed between a spring seat in the housing 1 I and the handle l9, partially overcomes the tension of the spring 4| and moves the handle to a trip indicating position as shown in Fig. 2.

With the parts in the tripped-open position as shown in full lines in Fig. 2, it is necessary, before the contacts can be closed, to engage the projections 45 back of the actuating member 3i.

This is accomplished by moving the handle I9 clockwise to the 01f position. During this movement the projections 45 wipe by the spaced ends 32 of the actuating member 3! which is then snapped back to the position in which it appears in Fig. 2 by the spring 33. The breaker may then be closed in the previously described manner by counter-clockwise movement of the handle to the on position.

The circuit breaker is opened instantaneously in response to overload currents of ten times or more of the normal rated current or in response to short circuit currents by means of an electromagnet 49 comprising a fixed magnet yoke 51 supported in recesses between the side wall of the housing i l and the cover i3 and an armature 53 secured to the bimetallic switch member 25 to the left of the pivot 21. I

Upon the occurrence of an overload current of ten times or more of normal rated current or a short circuit current the electromagnet 49 is energized by the current flowing through the bimetallic switch member, and attracts the armature 53 which causes instantaneous movement of the switch member 25 to the open position. This action also causes the toggle 33-25 to move overcenter in an upward direction to the position shown in Fig. 2 where the spring 33 biases the switch member 25 to the open position, and the spring 4'! moves the handle is to the trip indicating position. The breaker is then closed in the previously described manner by first moving the handle le -to the off position in order to position the projections 55 back of the ends 32 of the actuator 3| as shown in dot and dash lines in Fig. 2. The contacts are then closed by counter-clockwise movement of the handle l9 to the on position during which movement the projections 45 move the actuator 3i and thereby the toggle 33-25 overcenter in a downward direction and closes the contacts with a snap action.

The circuit breaker is trip-free of the handle. That is, the breaker will automatically trip open in response to overload circuits even if the handle is held in the closed position. The circuit breaker is of simple construction comprising a minimum number of parts that are inexpensive to manufacture, and are easily assembled and calibrated ince all of the parts are held in assembled relation by being received by recesses and projections on the base and cover of insulating material. The switch member which is constructed of bimetallic material constitutes the contact carrying means and the tripping means and also, together with the overcenter spring, comprises the means for automatically opening the contacts.

While the invention has been disclosed in ac cordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details and arrangement of parts thereof may be made without departing from some of the essential features of the invention.

We claim as our invention:

1. A circuit breaker comprising stationary and movable contacts, a thermally responsive switch member mounting said movable contact on one end thereof for movement into and out of engagement with said stationary contact, an overcenter spring cooperating with the other end of.

said thermally responsive switch member normally biasing said switch member to closed position, thermal bending of said switch member moving said overcenter spring to an overcenter position wherein said overcenter spring moves said switch member to open position to open said contacts with a snap action, a manual operating member movable to an open and to a closed position, and a joint between said overcenter spring and said thermally responsive switch member operable by said manual member to move said overcenter spring to another overcenter position wherein said spring moves said thermally responsive switch member to closed position to close said contacts with a snap action.

2. A circuit breaker comprising stationary and movable contacts, a thermally responsive switch member mounting said movable contact at one end thereof for movement into and out of engagement with said stationary contact, said thermally responsive switch member being connected to be traversed by the current of the circuit, spring means cooperating with the other end of said switch member normally biasing said thermally responsive switch member to closed position, means supporting said thermally responsive switch member at a point between its ends, thermal bending of said switch member moving said spring means to a position wherein said spring means acts to move said switch memher about said support means to an open position to effect opening of said contacts with a snap action.

3. A circuit breaker comprising stationary and movable contacts, a thermally responsive switch member mounting said movable contact at one end thereof for movement into and out of engagement with said stationary contact, said thermally responsive switch member being connected to be traversed by the current of the circuit,

spring means cooperating with the other end of said thermally responsive switch member :normally biasing said thermally responsive switch .member to closed position, means supporting said thermally responsive switch member at a point between its ends, thermal bending of'said thermally responsive switch member moving said spring means to a position wherein said spring means acts to move said switch member about said support-means to an open position to effect opening of said contacts'with a snap action, an actuatingmember disposed between said spring means and said switch member, and manually operable-means for engaging said actuating member and moving said spring means to a position where said spring means moves said switch member to effect closing of said contact with snap action 4. A circuit breakercompr-ising stationary and movable contacts, a thermally responsive switch member comprising a bimetallic member mounting said movable contact on one end thereofior movement into and out of engagement with said stationary contact, means supporting said bimetallic switch member at a point between its ends, spring means cooperating with the other end of said switch member to form a toggle hawing a normal overcenter position in which said spring means biases said bimetallic switch member closed, said toggle being movable to a sec ond 'overcenter position in which said spring means biases said switch member open, thermal bending of said bimetallic switch member moving said toggle to said second overcenter position to effect opening movement of said bimetallic switch member and opening of said contacts.

5. A circuit breaker comprising stationary and movable-contacts, a thermally responsive switch member comprising a bimetallic member mounting said movable contact on one end thereof for movement into and out of engagement with said stationary contact, means supporting said bimetallic switch member at a point between its ends, spring means cooperating with the other end of said switch member to form a toggle having a normal'overcenter position in which said spring means biases said switch member closed, said toggle being movable to a second overcenter position in which said spring means biases said switch member open, thermal bending of said bimetallic switch member moving said toggle to said second overcenter position to effect opening movement of said switch member and opening of said contacts, and manual means for engaging and moving said toggle to said normal overcenter position to effect closing movement of said bimetallic switch member and closing of said contacts.

6. A circuit breaker comprising stationary and movable contacts, a bimetallic switch member mounting said movable contact at one end thereof for movement into and out of engagement with said stationary contact, pivot means pivotally supporting said bimetallic switch member at a point between its ends, an overcenter spring cooperating with the other end of said bimetallic switch member to form a toggle, said toggle having a first overcenter position in which said overcenter spring biases said bimetallic switch member closed and a second overcenter position in which said overcenter spring biases said bimetallic switch member open, manual operating means including an operating handle movable to an "on and to an off position, a spring means connected under tension betweensaid handle and said toggle, said handle when moved to said "01? position increasing the tension of said spring means to cause movement of said toggle to said second overcenter position and opening movement of said bimetallic switch member, and means on said handle operable when said handle is moved to said on position to engage and positively move said toggle to said first overcenter position to effect closing movement of said bimetallic switch'member.

7. A circuit breaker comprising stationary and movable contacts, a bimetallic switch member mounting said movable contact at one end thereof for movement into and out of engagement with said stationary contact, pivot means pivotally supporting said bimetallic switch member at a point between its ends, an overcenter spring cooperating with the other end of said bimetallic switchrmember to form a toggle, said toggle having' a first overcenter position in which said overcenter spring biases said bimctal switch member closed and a second overcenter position in which said overcenter spring biases said bimetallic switch member open, manual operating means including an operating handle movable to an on and to an "on" position, a spring means connected under tension between said handle and said toggle, said handle when moved to said off position increasing the tension of said spring means to cause movement of said toggle to said second overcenter position and opening movement of said bimetallic switch member, and means on said handle operable when said handle is moved to said on position to engage and positively move said toggle to said first overcenter position to effect closing movement of said bimetallic switch member and thermal bending of said bimetallic switch member causing movement of said'togglcto said second overcenter position to eiiect automatic opening movement of said switch member.

8. A circuit breaker comprising a bimetallic switch member movable to open and close said circuitysaid bimetallic switch member being disposed to be heated by the current of the circuit, means supporting said bimetallic switch member at a point between the ends thereof, spring means cooperating with one end of said bimetallic switch member to form a toggle, said toggle having a normal position in which said spring means biases said bimetallic switch member closed and movable to a second position in which said spring means biases said bimetallic switch member open, thermal bending of said bimetallic switch when heated a predetermined amount in response to overload currents below a predetermined value moving said toggle to said second position to effect opening movement of said bimetallic switch member, electroresponsive means operable in response to overload currents above said predetermined value to move said toggle to said second position to effect instantaneous opening movement of said bimetallic switch member, and manual means movable to an oil and to an on position operable to engage and positively move said toggle to said normal position to move said bimetallic switch member to the closed position.

9. A circuit breaker comprising a housing, a switch member comprising a straight strip of bimetallic material movable to open and Close said circuit, pivot means pivotally supporting said bimetallic switch member at a point between the ends thereof, a compression spring compressed between said housing and one end of said bimetallic switch member and forming a toggle with 'said switch member, said toggle having a first position in which said compression spring biases said bimetallic switch member closed and a second position in which said spring member biases said bimetallic switch member open, manual operating means comprising a handle movable to an off and to an on position, a spring connected under an initial tension between said handle and said toggle, movement of said handle to said on position increasing the tension of said spring to cause overcenter movement of said toggle to said second position to efiect opening movement of said switch member, and said bimetallic switch member when heated by overload currents bending in a direction to cause movement or" said toggle to said second position to effect automatic opening movement of said switch member.

10. A circuit breaker comprising a housing, a switch member comprising a straight strip of bimetallic material movable to open and close said circuit, a pivot means pivotally supporting said bimetallic switch member at a point between the ends thereof, a compression spring compressed between said housing and one end of said bimetallic switch member and forming a toggle with said switch member, said toggle having a first position in which said compression spring biases said bimetallic switch member closed and a second position in which said spring member biases said bimetallic switch member open, manual operating means comprising a handle movable to an elf and to an on position, a spring connected under an initial tension between said handle and said toggle, movement of said handle to said off position increasing the tension of said spring to cause overcenter movement of said toggle to said second position to efiect opening movement of said bimetallic switch member, and said bimetallic switch member when heated by overload currents bending in a direction to cause movement of said toggle to said second position to efiect automatic opening movement of said bimetallic switch member and a projection on said handle'operable when said handle is moved to said "on position to engage and move said toggle to said first position to efiect closing movement of said switch member.

8 11. A circuit breaker comprising stationary and movable contacts, a bimetallic switch member mounting said movable contact on one end thereof for movement into and out of engagement with said stationary contact, pivot means pivotally supporting said bimetallic switch member at a point between the ends thereof, an overcenter spring cooperating with one end of said bimetallic switch member to form a toggle, said toggle having a first overcenter position in which said overcenter spring biases said bimetallic switch member closed and being movable to a second overcenter position in which said overcenter spring biases said switch member open, manual means movable to an on, an OE and to a trip indicating position, a tension spring connected with an initial tension between said handle and said toggle, said handle when moved to said off position increasing the tension of said tension spring to cause movement of said toggle to said second overcenter position to effect opening movement of said bimetallic switch member, means on said handle operable when said handle is moved to said on position to engage and move said toggle back to said first overcenter position to efiect closing movement of said bimetallic switch member, thermal bending of said bimetallic switch member causing automatic movement of said toggle to said second overcenter position to effect automatic opening movement of said bimetallic switch member, a compression spring biasing said handle to said trip indicating position, and automatic movement or" said toggle to said second overcenter position decreasing the tension of said tension spring to permit said compression spring to move said handle to said trip indicating position.

JOSEPH A. DROBNEY.

PAUL W. BROWN.

References Cited in the file of this patent UNITED STATES PAENTS Number Name Date 2,210,263 Sachs Aug. 6, 19 :0 2,212,732 Fisher Aug. 27, 1940 2,229,412 Jennings Jan. 21, 1941 

